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Abstract:

A vertical Hall sensor includes a Hall effect region and a plurality of
contacts formed in or on a surface of the Hall effect region. The
plurality of contacts are arranged in a sequence along a path extending
between a first end and a second end of the Hall effect region. The
plurality of contacts includes at least four spinning current contacts
and at least two supply-only contacts. The spinning current contacts are
configured to alternatingly function as supply contacts and sense
contacts according to a spinning current scheme. The at least four
spinning current contacts are arranged along a central portion of the
path. The at least two supply-only contacts are arranged on both sides of
the central portion in a distributed manner and are configured to supply
electrical energy to the Hall effect region according to an extension of
the spinning current scheme.

Claims:

1. A vertical Hall sensor, comprising: a Hall effect region; a plurality
of contacts formed in or on a surface of the Hall effect region, the
contacts being arranged in a sequence along a path extending between a
first end and a second end of the Hall effect region; wherein the
plurality of contacts comprise at least four spinning current contacts
and at least two supply-only contacts; wherein the spinning current
contacts are configured to alternatingly function as supply contacts and
sense contacts according to a spinning current scheme; wherein the at
least four spinning current contacts are arranged along a central portion
of the path; and wherein the at least two supply-only contacts are
arranged on opposing sides of the central portion in a distributed manner
and are configured to supply electrical energy to the Hall effect region
according to an extension of the spinning current scheme.

2. The vertical Hall sensor according to claim 1, wherein the Hall effect
region is elongated and has one of a straight shape, a curved shape, an
angled shape, an L-shape, an arched shape, and a piece-wise straight
shape.

3. The vertical Hall sensor according to claim 1, wherein the plurality
of contacts comprises at least four of the supply-only contacts so that
during at least two operating phases of the spinning current scheme at
least one supply-only contact at each side of the central portion is
configured to supply electrical energy to the Hall effect region.

4. The vertical Hall sensor according to claim 1, wherein the at least
two supply-only contacts comprise two outermost supply-only contacts that
are spaced apart from the first end and the second end by a distance
greater than a maximal spacing of the at least four spinning current
contacts.

5. The vertical Hall device according to claim 1, wherein a length of the
Hall effect region is greater than a length of the central portion by a
factor comprised in a range between 1.2 and 20.

6. The vertical Hall sensor according to claim 1, wherein two of the at
least four spinning current contacts and one of the at least two
supply-only contacts are configured to supply electrical energy to the
Hall effect region and two other spinning current contacts are configured
to function as sense contacts during a first operating phase of the
spinning current scheme, and wherein the two spinning current contact
functioning as sense contacts during the first operating phase and the
other of the at least two supply-only contacts are configured to supply
electrical energy to the Hall effect region, and the two spinning current
contacts having functioned as supply contacts during the first operating
phase are configured to function as sense contacts during a second
operating phase of the spinning current scheme.

7. The vertical Hall sensor according to claim 1, further comprising at
least two floating contacts, wherein a first of the at least two floating
contacts is formed in or on the surface of the Hall effect region between
the first end and one of the at least two supply-only contacts that is
closer to the first end than the other(s) of the at least two supply-only
contacts; and wherein a second floating contact of the at least two
floating contacts is formed in or on the surface of the Hall effect
region between the second end and one of the at least two supply-only
contacts that is closer to the second end than the other(s) of the at
least two supply-only contact.

8. The vertical Hall sensor according to claim 1, wherein the at least
four spinning current contacts comprise an odd number of spinning current
contacts equal to or greater than seven, wherein during at least one
operating phase of the spinning current scheme an even number equal to or
greater than four of the spinning current contacts are configured to
function as sense contacts, and wherein differential sense signals are
tapped between pairs of the spinning current contacts functioning as
sense contacts during said operating phase, wherein the pairs are
arranged along the path in a nested manner.

9. The vertical Hall sensor according to claim 1, further comprising a
further Hall effect region in, or on a surface of which, is formed a
further plurality of contacts similar to the plurality of contacts formed
in or on the surface of the Hall effect region, wherein the further
plurality of contacts is configured to function in a complementary manner
to the plurality of contacts, and wherein during each operating phase of
the spinning current scheme at least one first sensor signal is tapped
between at least two of the spinning current contacts of the plurality of
contacts formed in or on the surface of the Hall effect region and at
least one second sense signal is tapped between at least two spinning
current contacts of the further plurality of contacts formed in or on the
surface of the further Hall effect region, and wherein the at least one
first sense signal and the at least one second sense signal are added or
subtracted from each other by an output signal determiner of the vertical
Hall sensor.

10. The vertical Hall sensor according to claim 1 further comprising a
further Hall effect region and a further plurality of contacts formed in
or on the surface of a further Hall effect region, the plurality of
contacts and the further plurality of contacts being substantially
similar; wherein at least one sense signal is tapped between a spinning
current contact formed in or on the surface of the Hall effect region and
a spinning current contact formed in or on the surface of the further
Hall effect region, both functioning as a sense contact during a same
operating phase of the spinning current scheme.

11. The vertical Hall sensor according to claim 10, wherein the further
Hall effect region is substantially parallel to the Hall effect region,
and wherein the spinning current contacts of the Hall effect region and
the further Hall effect region between which the sense signal is tapped
have a corresponding position within the plurality of contacts and the
further plurality of contacts, respectively, and wherein a plurality of
the spinning current contacts functioning as supply contacts and of the
supply-only contact is inversed between the Hall effect region and the
further Hall effect region for a particular operating phase of the
spinning current scheme, so that directions of electrical current flow
are opposite to each other in corresponding portions of the Hall effect
region and the further Hall effect region.

12. The vertical Hall sensor according to claim 1, wherein the at least
two supply-only contacts comprise at least four switched supply-only
contacts, each one of the at least four switched supply-only contacts
being connected, through a switching element, to at least one of the at
least four spinning current contacts in accordance to the extension of
the spinning current scheme.

13. The vertical Hall sensor according to claim 1, further comprising a
plurality of floating contacts, wherein M floating contacts are arranged
between every two spinning current contacts, M being a positive integer.

14. A vertical Hall sensor, comprising: a Hall effect region; a plurality
of contacts formed in or on the Hall effect region in a sequence along a
path extending between a first end and a second end of the Hall effect
region, wherein the contacts are consecutively numbered according to the
sequence, the plurality of contacts comprising first type contacts and
second type contacts, wherein M second type contacts are arranged between
every two first type contacts, M being a positive integer; wherein first
type contacts having ordinal numbers within the sequence given by
1+i*4*(1+M), i=0, 1, 2 . . . are connected to a first node N1; wherein
first type contacts having ordinal numbers within the sequence given by
2+M+i*4*(1+M), i=0, 1, 2 . . . are connected to a second node N2; wherein
first type contacts having ordinal numbers within the sequence given by
3+2*M+i*4*(1+M), i=0, 1, 2 . . . are connected to a third node N3; and
wherein first type contacts having ordinal numbers within the sequence
given by 4+3*M+i*4*(1+M), i=0, 1, 2 . . . are connected to a fourth node
N4; wherein the first type contacts are configured to alternatingly
function as supply contacts and sense contacts according to a spinning
current scheme with provision to supply electrical energy between the
first nodes N1 and third nodes N3 in a first operating phase of the
spinning current scheme and between the second nodes N2 and fourth nodes
N4 in a second operating phase, and to sense a sense signal between the
second nodes N2 and fourth nodes N4 in the first operating phase and to
sense another sense signal between the first nodes N1 and third nodes N3
in the second operating phase; and wherein the second type contacts are
floating contacts.

15. The vertical Hall sensor according to claim 14, wherein the second
type contacts have a different shape than the first type contacts.

16. The vertical Hall sensor according to claim 14, wherein the second
type contacts have an extension in a direction perpendicular to the path
smaller than a corresponding extension of the first type contact.

17. The vertical Hall sensor according to claim 14, wherein the Hall
effect region is elongated and wherein the first type contacts and the
second type contacts are symmetrical with respect to a middle line of the
Hall effect region extending between the first end and the second end.

18. The vertical Hall sensor according to claim 14, wherein the second
type contacts comprise a first group and a second group, wherein the
second type contacts of the first group are connected to a first floating
node and the second type contacts of the second group are connected to a
second, different floating node.

19. The vertical Hall sensor according to claim 14, further comprising at
least one switching element configured to selectively connect at least
one of the first type nodes with the corresponding nodes of the first
node, second node, third node, and fourth node.

20. The vertical Hall sensor according to claim 14, wherein the Hall
effect region is elongated and has one of a straight shape, a curved
shape, an angled shape, an L-shape, an arched-shape, and a piece-wise
straight shape.

21. The vertical Hall sensor according to claim 14, wherein the plurality
of contacts comprises a first outermost contact and a second outermost
contact, the first outermost contact being at a first distance from the
first end and the second outermost contact being at a second distance
from the second end, wherein the first distance and the second distance
are greater than a maximal spacing of the first type contacts.

22. The vertical Hall sensor according to claim 14, further comprising a
further Hall effect region in, or on a surface of which, is formed a
further plurality of contacts similar to the plurality of contacts formed
in or on the surface of the Hall effect region, wherein the further
plurality of contacts is configured to function in a complementary manner
to the plurality of contacts, and wherein during each operating phase of
the spinning current scheme at least one first sensor signal is tapped
between at least two of the first type contacts of the plurality of
contacts formed in or on the surface of the Hall effect region and at
least one second sense signal is tapped between at least two first type
contacts of the further plurality of contacts formed in or on the surface
of the further Hall effect region, and wherein the at least one first
sense signal and the at least one second sense signal are added or
subtracted from each other by an output signal determiner of the vertical
Hall sensor.

23. The vertical Hall sensor according to claim 14, further comprising a
further Hall effect region and a further plurality of contacts formed in
or on the surface of a further Hall effect region, the plurality of
contacts and the further plurality of contacts being substantially
similar; wherein at least one sense signal is tapped between a spinning
current contact formed in or on the surface of the Hall effect region and
a spinning current contact formed in or on the surface of the further
Hall effect region, both functioning as a sense contact during a same
operating phase of the spinning current scheme.

24. The vertical Hall sensor according to claim 14, wherein the plurality
of contacts comprises at least two supply-only contacts as the outermost
contacts of the plurality of contacts, the supply-only contacts being
configured to supply electrical energy to the Hall effect region
according to an extension of the spinning current scheme.

25. A vertical Hall sensor, comprising: a Hall effect region having a
first end and a second end and being symmetric with respect to a symmetry
axis such that the first and second ends are mirror-inverted to each
other with respect to the symmetry axis; a plurality of contacts formed
in or on a surface of the Hall effect region in a symmetrical manner with
respect to the symmetry axis, the contacts being arranged in a sequence
along a path extending between the first end and the second end of the
Hall effect region; wherein the plurality of contacts comprises at least
four spinning current contacts and at least two supply-only contacts;
wherein the spinning current contacts are configured to alternatingly
function as supply contacts and sense contacts according to a spinning
current scheme; wherein the at least four spinning current contacts are
closer to the symmetry axis than the supply-only contacts; wherein the at
least two supply-only contacts are configured to supply electrical energy
to the Hall effect region such that boundary effects affecting an
electric current flow within the Hall effect region during an execution
of the spinning current scheme are reduced, the boundary effects being
caused by at least one of the first and second ends.

26. A magnetic sensing method, comprising: connecting a power supply
between a spinning current contact and a supply-only contact, wherein the
spinning current contact is configured to alternatingly function as a
supply contact and a sense contact according to a spinning current
scheme, wherein the spinning current contact and the sense contact belong
to a plurality of contacts formed in or on the surface of a Hall effect
region of a vertical Hall sensor comprising at least four spinning
current contacts and at least two supply-only contacts, the contacts
being arranged in a sequence along a path extending between a first end
and a second end of the Hall effect region, wherein the at least four
spinning current contacts are arranged along a central portion of the
path, and wherein the at least two supply-only contacts are arranged on
both sides of the central portion in a distributed manner and are
configured to supply electrical energy to the Hall effect region
according to an extension of the spinning current scheme for supplying
electrical energy to the Hall effect region; sensing a sense signal
between at least two spinning current contacts currently functioning as
sense contacts; swapping the functions of the spinning current contacts
so that the electrical energy is now supplied to the Hall effect region
via one of the spinning current contacts having previously functioned as
sense contacts and at least one other supply-only contact different from
the supply-only contact used previously; sensing a sense signal between
two spinning current contacts other than the ones used previously; and
determining an output signal based on the sense signals.

27. The magnetic sensing method according to claim 26, wherein
determining the output signal comprises multiplying at least one of the
sense signals with .+-.1 and at least one of adding, averaging, and
low-pass filtering two or more sense signals.

28. The magnetic sensing method according to claim 26, further
comprising: switching at least one switching element connected to at
least one of the supply-only contacts so that the at least one
supply-only contact is configured to supply electrical energy to the Hall
effect region during at least one operating phase of the spinning current
scheme and to function as a floating contact during at least one other
operating phase of the spinning current scheme.

[0002] Embodiments of the present invention relate to a vertical Hall
sensor and to a magnetic sensing method using a vertical Hall sensor.

BACKGROUND OF THE INVENTION

[0003] In order to sense or measure the strength and direction of a
magnetic field parallel to the surface of, e.g., a semiconductor die,
vertical Hall devices may be used. Most vertical Hall devices suffer from
the fact that the spinning current method, which is used to cancel the
zero-point error of the Hall devices, does not work very well. With known
methods of the spinning current scheme, it is possible to obtain residual
zero-point errors of about 1 mT. A reason for this rather poor offset
behavior can be found in the asymmetry of the vertical Hall device.
Although it is known how to connect four vertical Hall devices in order
to improve the symmetry, the contact resistances may still cause residual
asymmetries.

SUMMARY

[0004] Embodiments of the present invention provide a vertical Hall sensor
that comprises a Hall effect region and a plurality of contacts formed in
or on a surface of the Hall effect region. The contacts are arranged in a
sequence along a path extending between a first and a second end of the
Hall effect region. The plurality of contacts comprise at least four
spinning current contacts and at least two supply-only contacts. The
spinning current contacts are configured to alternatingly function as a
supply contact and a sensor contact according to a spinning current
scheme. The at least four spinning current contacts are arranged along a
central portion of the path. The at least two supply-only contacts are
arranged on both sides of the central portion in a distributed manner and
are configured to supply electrical energy to the Hall effect region
according to an extension of the spinning current scheme for supplying
electrical energy to the Hall effect region.

[0005] Further embodiments of the present invention provide a vertical
Hall sensor comprising a Hall effect region and a plurality of contacts
formed in or on a Hall effect region in a sequence along a path extending
between a first end and a second end of the Hall effect region. The
contacts are consecutively numbered according to the sequence. The
plurality of contacts comprises first type contacts and second type
contacts, wherein M second type contacts are arranged between every two
first type contacts, M being a positive integer. First type contacts
having ordinal numbers within the sequence given by 1+i*4*(1+M), i=0, 1,
2 . . . are connected to a first node N1. First type contacts having
ordinal numbers within the sequence given by 2+M+i*4*(1+M), i=0, 1, 2 . .
. are connected to a second node N2. First type contacts having ordinal
numbers within the sequence given by 3+2*M+i*4*(1+M), i=0, 1, 2 . . . are
connected to a third node N3. Finally, first type contacts having ordinal
numbers within the sequence given by 4+3*M+i*4*(1+M), i=0, 1, 2 . . . are
connected to a fourth node N4. The first type contacts are considered to
alternatingly function as supply contacts and as sense contacts according
to a spinning current scheme with provision to supply electrical energy
between the first and third nodes N1, N3 in a first operating phase of
the spinning current scheme and between the second and fourth nodes N2,
N4 in a second operating phase. The first type contacts are also
configured to sense a sense signal between the second and fourth nodes
N2, N4 in the first operating phase and to sense another sense signal
between the first and third nodes N1, N3 in the second operating phase.
The second type contacts are floating contacts.

[0006] Further embodiments of the present invention provide a vertical
Hall sensor comprising a Hall effect region and a plurality of contacts
formed in or on a surface of the Hall effect region. The Hall effect
region has a first end and a second end. The Hall effect region is
symmetric with respect to a symmetry axis such that the first and the
second ends are mirror-inverted to each other with respect to the
symmetry axis. The plurality of contacts are formed in a symmetrical
manner with respect to the symmetry axis. The contacts are arranged in a
sequence along a path extending between the first end and the second end
of the Hall effect region. The plurality of contacts comprises at least
four spinning current contacts and at least two supply-only contacts. The
spinning current contacts are configured to alternatingly function as
supply contacts and as sensor contacts according to the spinning current
scheme. The at least four spinning current contacts are closer to the
symmetry axis than the supply-only contacts. The at least two supply-only
contacts are configured to supply electrical energy to the Hall effect
region such that boundary effects affecting an electric current flow
within the Hall effect region during an execution of a spinning current
scheme are reduced, the boundary effects being caused by at least one of
the first and second ends.

[0007] Furthermore, embodiments of the present invention provide a
magnetic sensing method which comprises connecting a power supply between
a spinning current contact and a supply-only contact, sensing a sense
signal, swapping the functions of the spinning current contacts, sensing
another sense signal, and determining an output signal. The spinning
current contact is configured to alternatingly function as a supply
contact and as a sense contact according to the spinning current scheme.
The spinning current contact and the sense contact belong to a plurality
of contacts formed in or on a surface of a Hall effect region of a
vertical Hall sensor. The plurality of contacts comprises at least four
spinning current contacts and at least two supply-only contacts. The
contacts are arranged in a sequence along a path extending between a
first end and a second end of the Hall effect region, wherein the at
least four spinning current contacts are arranged along a central portion
of the path. The at least two supply-only contacts are arranged on both
sides of the central portion in a distributed manner and are configured
to supply electrical energy to the Hall effect region according to an
extension of the spinning current scheme for supplying electrical energy
to the Hall effect region. The action of sensing a sense signal is
performed between at least two spinning current contacts currently
functioning as sense contacts. The action of swapping the functions of
the spinning current contacts has the effect that the electrical energy
is now supplied to the Hall effect region via the spinning current
contacts having previously functioned as sense contacts and at least one
other supply-only contact different from the supply-only contact used
before. The other sense signal is sensed between two spinning current
contacts other than the ones used previously. The output signal is
determined on the basis of the sense signals.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Embodiments of the present invention are described herein, making
reference to the appended drawings.

[0009] FIG. 1a shows a schematic plan view and a corresponding schematic
cross section of a vertical Hall sensor during a first operating phase
(top) and a second operating phase (bottom) of a spinning current scheme;

[0010] FIG. 1b shows a schematic plan view of a vertical Hall sensor using
one supply contact more in the first and second operating phase than the
vertical Hall sensor shown in FIG. 1a;

[0011] FIG. 1c shows schematic plan views of a vertical Hall effect sensor
according to an embodiment of the teachings disclosed herein in a first
and a second operating phase, respectively;

[0012]FIG. 1D shows schematic plan views of a vertical Hall sensor during
a first and a second operating phase, respectively, to illustrate how
differential sensor signals may be tapped at the sensor contacts in a
nested manner;

[0013]FIG. 2 illustrates an extension of tapping differential sensor
signals at the sense contact in a nested manner;

[0014] FIG. 3 shows schematic plan views of a vertical Hall device having
two Hall effect regions in a first and a second operating phase,
respectively;

[0015] FIG. 4 shows schematic plan views of another vertical Hall sensor
having two Hall effect regions in a first and a second operating phase,
respectively;

[0016] FIG. 5 shows schematic plan views of a vertical Hall sensor having
two Hall effect regions according to an embodiment of the disclosed
teachings in a first and a second operating phase, respectively;

[0017] FIG. 6 shows schematic plan views of vertical Hall sensors in a
first and a second operating phase, respectively;

[0018] FIG. 7 shows schematic plan views of a vertical Hall sensor
according to an embodiment of the disclosed teachings during a first and
a second operating phase, respectively;

[0019]FIG. 8 shows a schematic plan view of a vertical Hall sensor with
an L-shaped Hall effect region according to an embodiment of the
disclosed teachings;

[0020]FIG. 9 shows a schematic plan view of a vertical Hall sensor having
an arch-shaped Hall effect region according to an embodiment of the
disclosed teachings;

[0021] FIG. 10 shows schematic plan views of a Hall effect sensor
according to an embodiment of the disclosed teachings during a first and
a second operating phase, respectively;

[0022]FIG. 11 shows a schematic plan view of a vertical Hall sensor
according to an embodiment of the disclosed teachings similar to the one
shown in FIG. 11;

[0026] FIGS. 13a, 13b show a vertical Hall sensor having a square,
ring-like Hall effect region in a first operating state and a second
operating state of the spinning current scheme;

[0027] FIGS. 14a, 14b show another vertical Hall sensor having a
ring-like, square Hall effect region during a first operating phase and a
second operating phase, respectively; and

[0028]FIG. 15 shows a schematic flow diagram of a magnetic sensing method
according to an embodiment of the disclosed teachings.

[0029] Equal or equivalent elements or elements with equal or equivalent
functionality are denoted in the following description by equal or
similar reference signs.

DETAILED DESCRIPTION

[0030] In the following description, a plurality of details are set forth
to provide a more thorough explanation of embodiments of the teachings
disclosed herein. However, it will be apparent to one skilled in the art
that embodiments of the teachings disclosed herein may be practiced
without these specific details. Features of the different embodiments
described hereinafter may be combined with each other, unless
specifically noted otherwise. For the most part, the terms "Hall effect
region" and "tub" are used interchangeably herein. Accordingly, a Hall
effect region may be a tub or a well of a first conductivity type which
is embedded in a substrate or a tub of an opposite conductivity type.
This structure may cause an electrical isolation of the tub against the
substrate in particular if the resulting PN-junction is reversed biased.

[0031] When the vertical Hall sensor comprises two or more Hall effect
regions, these may be isolated from each other. The electrical isolation
of two Hall effect regions against each other may take several forms.
According to a first form of isolation, the two or more Hall effect
regions are disjoined from each other, i.e., two adjacent Hall effect
regions do not merge at one or more locations but are separated by a
material other than the Hall effect region material. As one possible
option, the tub may be isolated in a lateral direction by means of
trenches that are typically lined and/or filled with a (thin) oxide. As
another option, the tub may be isolated towards the bottom by means of an
SOI (silicon on insulator) structure. Although the tub typically has a
single conductivity type, it may be advantageous to configure the doping
concentration in an inhomogeneous manner, i.e., spatially variable. In
this manner, a high concentration of the doping agent may occur in the
area of the contact, as is usual with deep tub contacts, for example in
CMOS technology. In the alternative, a layering of differently strongly
doped layers may be sought after as is the case with, e.g., a buried
layer. Such a layering may result, to some extent, from technological
reasons relative to other electronic structures that are formed within
the substrate. The design of the vertical Hall sensor may need to be
reconciled with these circumstances, even though the layering may, in
fact, be unfavorable for the vertical Hall sensor.

[0032] Another form of isolation may be achieved by measures that reduce
or substantially prevent an electric current from flowing in one or more
subregions of a tub or well. For example, the electric current may be
offered an alternative current path that has lower ohmic resistance
(possibly by several orders of magnitude) than a substantially parallel
current path would have that goes through the tub. The current path
having the lower ohmic resistance may be a conductor formed in or on the
surface of the tub.

[0033] Preferably, the Hall effect region may be an n-doped semiconductor
as this provides an approximately three times higher mobility and
consequently a higher Hall factor than with a p-doped semiconductor. The
doping concentration in the functional part of the Hall effect region is
typically in the range of 1015 cm-3 to 1017 cm3.

[0034] Another possible material for the Hall effect regions is permalloy
which is a nickel-iron magnetic alloy, or a material similar to
permalloy. Permalloy exhibits a low coercivity, near zero
magnetostriction, high magnetic permeability, and significant anisotropic
magnetoresistance. A variation of the electrical resistance of permalloy
within a range of approximately 5% can typically be observed depending on
the strength and the direction of an applied magnetic field. This effect
may be used in a similar manner as the Hall effect occurring in a
semiconductor for sensing and/or measuring a magnetic field, and it is
known in the literature as anomalous Hall effect.

[0035] The teachings disclosed herein are related to the use of the
spinning current principle, in which supply terminals and sense terminals
are exchanged in consecutive clock phases/operating phases. A sense
terminal in a vertical Hall sensor responds to an electric current
passing underneath it. A magnetic field (parallel to a die surface and
perpendicular to the current streamline) can efficiently lift up or pull
down the potential at the contact (which typically is at the surface of
the die). Contacts at the end of a tub (or a Hall effect region)
typically are not, or only negligibly, subject to current streamlines
passing underneath them. Therefore, contacts at the ends of a tub
typically are less frequently used as sense contacts.

[0036] When using the spinning current principle for vertical Hall
devices, one challenge is the fact that typical vertical Hall devices are
not symmetric, in terms of an interchangeability of supply contacts and
sense contacts. However, the spinning current principle typically needs a
highly symmetric device. A typical vertical Hall device may have a shape
of a brick with several contacts. Some of the contacts are closer to one
of the ends of the brick than other (more central) contacts. For this
reason the outer contacts, when used as supply contacts, generate
different potential distributions in the brick than the inner contacts.
Therefore, if the spinning current principle periodically exchanges input
with output terminals, the symmetry of the potential distributions will
be poor.

[0037] According to one aspect of the teachings disclosed herein, the
brick may be stretched and only the inner contacts may be used so that
the outer contacts are far away and are not used for the output signal
while the inner contacts are almost perfectly symmetric.

[0038] Besides sensing Hall effect-related sense signals primarily in a
central portion of the Hall effect region, i.e., typically relatively far
away from a first end and a second end of a Hall effect region with
respect to a longitudinal direction, the following measures may also
favor a more symmetric behavior of the vertical Hall sensor: using
supply-only contacts and/or providing floating contacts between each two
(adjacent) spinning current contacts. Typically, there is an even number
of the supply-only contacts with one half of the supply-only contacts
being arranged at one side of a central region in which the spinning
current contacts are located, and the other half being arranged on the
other side of the central region, in order to maintain the symmetry of
the vertical Hall sensor. Vertical Hall sensors having four supply-only
contacts appear to perform quite well with respect to improving the
symmetry of the vertical Hall sensor and thus reducing the residual
zero-point error. Nevertheless, embodiments having only two supply-only
contacts may be conceived as well. Likewise, vertical Hall sensors having
six or more supply-only contacts may also be designed. In the vicinity of
each supply-only contact, the current density distribution may be subject
to influences caused by either the first end or the second end of the
Hall effect region, whichever is closer to the supply-only contact at
hand. When approaching the central region and within the central region,
however, the current density distribution becomes more and more
homogeneous. In other words, local irregularities caused by the first end
or the second end of the Hall effect region have only a relatively small
influence on the current density distribution in the central region of
the Hall effect region. Another possible reason for an inhomogeneous
current density distribution within the Hall effect region may be found
in the need for the electric current to change its direction of current
flow twice while flowing through the Hall effect region. This phenomenon
is believed to not only affect those supply contacts or supply-only
contacts that are relatively close to the first end or the second end of
the Hall effect region, but basically all supply contacts and supply-only
contacts. The supply-only contacts, that are relatively far away from the
central region of the Hall effect region, may level out, on average, the
irregularities in the current density distribution within the central
region up to a certain degree. In particular, the current density
distribution in the central region during the first operating phase is
typically much more similar to the current density distribution within
the central portion during the second operating phase, except for the
fact that the direction of current flow may be opposite in the second
operating phase compared to the first operating phase, at least in some
sections of the Hall effect region. This inversion of the current flow
is, however, intentional and may be taken into account when determining
the output signal of the vertical Hall sensor. In summary, the symmetry
of the device can be increased by means of the supply-only contacts at
the expense of a slightly increased current consumption.

[0039] According to the teachings disclosed herein, it is also possible to
provide one or more floating contacts between each two adjacent spinning
current contacts. These floating contacts are also called second type
contacts in other parts of this disclosure. Floating contacts are
low-ohmic compact regions at the surface (i.e., an accessible side) of
the Hall effect region that are neither used for the purpose of supplying
electrical energy nor for tapping a sense signal. Floating contacts may
be used to influence the electric potential in the well similar to the
gate of a CMOS transistor. As an alternative, the floating contacts could
be highly doped wells that are not necessarily contacted to a metal
region. Yet another alternative is that the floating contacts could be
wells having a high doping concentration that are contacted to one or
more metal spots by means of a contact plug. The floating contacts have
the following effect: the current flow is pulled closer to a middle line
of the Hall effect region extending between the first end and the second
end in a substantially parallel or coinciding manner with the path along
which the spinning current contacts (first type contacts) and the
floating contacts (second type contacts) are arranged. Floating contacts
that are smaller than the spinning current contacts and/or the
supply-only contacts are particularly efficient in concentrating the
current flow around the middle line of the Hall effect region. Note that
the desired homogeneity of the current flow is mainly important in the
longitudinal direction, i.e. parallel to the path along which the
contacts are arranged. Pulling the current flow towards the middle line
may be important when, due to process technological reasons it is not
possible that the first type contacts extend over the entire width of the
Hall effect region: in this case, the magnetic sensitivity is reduced due
to portions of the electric current that flow in a direction parallel to
the component of the magnetic field to be sensed (i.e., the y-direction
according to the coordinate system used in most of the figures). In order
to prevent/avoid these portions of the current, the floating contacts are
arranged near the middle line which pull the current to the middle.

[0040] FIG. 1a shows, in the upper half, a schematic plan view of a
vertical Hall sensor and a corresponding cross-section of the same
vertical Hall sensor during a first operating phase or clock phase of a
spinning current scheme or cycle. In the lower half, FIG. 1a shows the
schematic plan view and a schematic cross-section of the same vertical
Hall sensor during a second operating phase of the spinning current
scheme. The vertical Hall sensor comprises a Hall effect region 11 that
may be formed in a semiconductor substrate by locally doping the
semiconductor substrate to obtain, e.g., an n-type semiconductor material
(an n-type semiconductor has more electrons than holes). By locally
doping the semiconductor substrate a well or a tub is formed within the
semiconductor substrate. The well or tub may then be used as the Hall
effect region 11. A plurality of contacts is formed in, or on a surface
of, the Hall effect region 11. The plurality of contacts in one
embodiment comprises four spinning current contacts 21, 22, 23, and 24.
During the first operating phase of the vertical Hall sensor, the
spinning current contacts 21 and 22 function as supply contacts. To this
end, the spinning current contacts 21 and 22 are connected to a voltage
supply 81. As an alternative to the voltage supply 81, a current source
could be used as well. The two other spinning current contacts 23 and 24
are configured to function, during the first operating phase, as sense
contacts so that they are connected to a voltage sensing element 91.
During operation, the voltage supply 81 causes an electric current to
flow to the spinning current contact 21 (supply voltage in operating
phase 1), through a portion of the Hall effect region 11, thereby passing
the spinning current contact 24 (sense contact), to the spinning current
contact 22 (supply contact), and back to the voltage supply 81. A
magnetic field By in the y-direction, i.e., parallel to the surface of
the Hall effect region 11 and perpendicular to a longitudinal extension
of the Hall effect region 11, has an influence on the electric charge
carriers constituting the electric current within the portion of the Hall
effect region extending between the supply contacts 22 and 21. A result
of this influence is a variation of an electric potential at the sense
contact 24, wherein the variation is a function of the magnetic field By
in the y-direction. The variation of the electric potential at the sense
contact 24 is referred to the sense contact 23 and a corresponding
differential electric voltage can be sensed by the sensing element 91.

[0041] The contacts that are formed in or on the surface of the Hall
effect region 11 may be referred to either by their reference numeral or
by their ordinal number. Whenever possible, the reference numbers have
been assigned (by definition) to the various contacts on the basis of a
function of the particular contact during the first operating phase. For
example, the spinning current contacts 21 to 24 have reference numerals
in the 20s, whereas supply-only contacts have reference numbers in the
30s. In contrast, the ordinal numbers reflect a spatial arrangement of
the contacts. The contacts may be thought of as arranged in a sequence
along a path extending between a first end and a second end of the Hall
effect region 11. In the figures the ordinal numbers are the numbers
which are illustrated directly adjacent or within the corresponding
contact. The ordinal numbers have an ascending order typically from left
to right. To give an example: the spinning current contact 21 has the
ordinal number 6. As a shorthand notation for the ordinal numbers the
hash key symbol # will be used, e.g., "contact #6" for the just mentioned
spinning current contact 21 which is at the sixth position from the left.

[0042] In the figures, an effort has been made to indicate a function of
each contact during the operating phases of the spinning current scheme.
Spinning current contacts currently functioning as supply contacts are
solid white or solid black, depending on the pole of the voltage supply
81 they are connected to (positive pole: black; negative pole: white).
Spinning current contacts currently functioning as sense contacts have a
relatively dark, upward hatching (e.g., spinning current contact 23) or a
relatively light, downward hatching (e.g., spinning current contact 24),
depending on the pole of the sensing element 91 to which a particular
sense contact is connected. Supply-only contacts, which will be explained
in more detail below, are also solid white or solid black, depending on
how they are connected to the voltage supply 81. Contacts that are
floating during the first operating phase may have one of the following
four patterns: small checkerboard pattern (e.g., contact with ordinal
number 2), cross-hatching (e.g., contact with ordinal number 8), dense
vertical hatching (e.g., contact with ordinal number 3), and horizontal
hatching (e.g., contacts with ordinal numbers 1 and 9); these assignments
being valid for FIG. 1a and not necessarily for other figures).

[0043] The vertical Hall sensor shown in FIG. 1a comprises a plurality of
floating contacts 64-1, 61, 63, 62, and 64-2. The floating contacts 64-1,
61, and 63 are arranged on one side of the four spinning current contacts
21 to 24. The other two floating contacts 62 and 64-2 are arranged on
another side of the four spinning current contacts 21 to 24. Due to the
floating contacts 61, 62, 63, 64-1, and 64-2, the regular contact
structure that is formed in or on the surface of the Hall effect region
11 does not abruptly end at the two outer spinning current contacts 22
and 23, but is continued (or extrapolated) for a few contacts. Thus, a
distance between the two outer spinning current contacts 22, 23 to the
first end or the second end of the Hall effect region 11 can be increased
without introducing another source for inhomogeneity at the edges of a
central portion of the Hall effect region 11 in which the four spinning
current contacts 21 to 24 are arranged.

[0044] The lower half of FIG. 1a shows the vertical Hall sensor during a
second operating phase of the spinning current scheme. The functions of
the spinning current contacts 21 to 24 have been swapped so that the
voltage supply 81 is now connected to spinning current contacts 23, 24,
while the sensing element 91 is connected to the spinning current
contacts 21, 22. Following the principle that a fill pattern of a contact
typically illustrates its current function, the spinning current contact
23 is illustrated as solid black, the spinning current contact 24 is
illustrated as solid white, the spinning current contact 21 is
illustrated with a dark, upward hatching, and the spinning current
contact 22 is illustrated with a bright, dark numbered hatching. Although
they are not connected to any other circuitry in FIG. 1a, the fill
patterns of the floating contacts 61, 62, 63, 64-1 and 64-2 are also
changed in the lower half of FIG. 1a with respect to the upper half
thereof.

[0045] The operation of the vertical Hall sensor shown in FIG. 1a may be
described as follows: in a first clock phase (operating phase) a voltage
source 81 is connected to two inputs having the ordinal numbers 4 and 6.
A sense element or voltmeter 91 is connected to the two outputs with the
ordinal numbers 5 and 7. In the second operating phase, the inputs and
the outputs are exchanged: the voltage source 81 is connected to the two
inputs with the ordinal numbers 5 and 7 and the voltmeter 91 (or another
voltmeter) is connected to the two outputs with ordinal numbers 4 and 6.
In an optional third operating phase, the voltage source 81 and the
voltmeter 91 are connected to the same contacts as in the first operating
phase, but with reversed polarity. In an optional fourth operating phase
the voltage source 81 and the voltmeter 91 (or the other voltmeter) are
connected to the same contacts as in the second operating phase, but with
reversed polarity. All other contacts (i.e., contacts with the ordinal
numbers 1, 2, 8, and 9) are left floating. Instead of measuring the
differential output voltage between the contacts with ordinal numbers 5
and 7 in the first operating phase, one may measure only the electric
potential at the contact having ordinal number 5 (referred to ground
potential). Analogously, instead of measuring the differential output
voltage between the contacts with ordinal numbers 4 and 6 in the second
operating phase, one may measure only the electric potential at the
contact with ordinal number 6.

[0046] Note that the Hall effect region 11 extends beyond the outmost
contacts 64-1 and 64-2. This is done in order to reduce the asymmetry of
the outer contacts 64-1, 64-2, when compared with the inner contacts.
Note also that several outer contacts are not in use, meaning that they
are not supplied with electricity and there is no (volt) meter connected
to them: they are simply floating. They are used only for the purpose of
minimizing the asymmetry of the outer contacts. Effectively, only the
four spinning current contacts 21 to 24 are in use and the role of inputs
and outputs is exchanged in the two operating phases. The contacts are
typically identical in size and are arranged on a regular grid and
positioned in a symmetric manner with respect to the Hall effect region
11 in order to maximize their symmetry. The two outmost contacts 64-1 and
64-2 could be short-circuited (i.e., connected by a conductor) in one
embodiment, in order to increase the symmetry (short-circuit not shown in
FIG. 1a).

[0047] FIG. 1b shows two schematic plan views of a vertical Hall sensor
according to an embodiment of the teachings disclosed herein in a first
operating phase (top) and a second operating phase (bottom). In
comparison to the vertical Hall sensor shown in FIG. 1a, the vertical
Hall sensor shown in FIG. 1b is more symmetric. In the configuration of a
vertical Hall sensor shown in FIG. 1b, some of the outer contacts are
used to apply the electric energy to the device, in order to increase the
symmetry of the potential distribution. The improved vertical Hall stripe
shown in FIG. 1b comprises nine identical contacts in a Hall effect
region 11 arranged on a regular grid along the x-axis in order to measure
magnetic fields in the y-direction By. The vertical Hall sensor is the
same as in FIG. 1a, but the supply voltage is connected to one more
contact: in the first operating phase a contact 32 (ordinal number 8) is
additionally grounded and in the second operating phase a contact 31
(ordinal number 3) is additionally tied to positive supply voltage as
this gives a better symmetry between contacts 24 and 23 (#5 and #7,
respectively) in operating phase 1 and between contacts 22 and 21 (#4 and
#6, respectively). Therefore, at zero magnetic field By the output
voltages in operating phase 1 and operating phase 2 are much closer to
zero than in FIG. 1a.

[0048] The contacts 31 and 32 are supply-only contacts, because they are
only used as supply contacts throughout the spinning current scheme, but
not as sense contacts (extension of the spinning current scheme or
generalization thereof). The two supply-only contacts 31, 32 are arranged
on both sides of a central portion of the plurality of contacts. The four
spinning current contacts 22, 24, 21, and 23 are located in the central
portion. The two supply-only contacts 31 and 32 are arranged on both
sides of the central portion in a distributed manner, i.e., there are
substantially as many supply-only contacts on a first side of the central
portion as on the second side thereof. The length of the Hall effect
region 11 may be greater than a corresponding length of the central
portion by a factor comprised in a range between 1.2 and 20, or a
narrower range such as between 1.5 and 15, between 2 and 10, or between 3
and 8. Supply-only contacts serve to supply electric energy in at least
one of the operating phases of the spinning current scheme, but they do
not serve to sense a sense signal during other operating phase(s). For
example, they may be floating during the other operating phase(s).

[0049] The vertical Hall sensor comprises a second voltage supply 82 that
is connected to the spinning current contacts 21 and 22 during the first
operating phase and to the spinning current contacts 23 and 24 during the
second operating phase of the spinning current scheme.

[0050] Note that the contacts are symmetrical to the Hall effect region 11
in operating phase 2, but not in operating phase 1: one might take
account of this by making the Hall effect region 11 slightly shorter at
the left side.

[0051] It is also possible to supply additionally the contact 61 (#2) with
positive supply voltage in operating phase 1 and the contacts 64-1, 64-2
(#1 and #9, respectively) with the electric ground potential in operating
phase 2, in order to make the potential distribution even more symmetric
in both operating phases. This becomes apparent when looking at the
vertical Hall sensor from the perspective of the output contacts 23 and
24 (#5 and #7, respectively) in operating phase 1 and from the
perspective of the contacts 21 and 22 (#4 and #6, respectively) in
operating phase 2.

[0052] According to the embodiments shown in FIG. 1b, the outmost contacts
64-1 and 64-2 are not used as inputs for electrical energy. Instead, the
outmost contacts 64-1, 64-2 are floating contacts. Another floating
contact is contact 61 (#2). In particular, a first floating contact 64-1
of the at least two floating contacts 61, 64-1, 64-2 may be formed in or
on the surface of the Hall effect region 11 between the first end and one
supply-only contact 31 of the at least two supply-only contacts 31, 32
that is closer to the first end than the other(s) of the at least two
supply-only contacts. A second floating contact 64-2 of the at least two
floating contacts is formed in or on the surface of the Hall effect
region 11 between the second end and one supply-only contact 32 of the at
least two supply-only contacts that is closer to the second end than the
other(s) of the at least two supply-only contact.

[0053] In cases where the outmost contacts and/or contacts that are not
the outmost contacts, but nevertheless relatively far out, are used as
supply contacts, it may be possible to use a different input voltage or
current for these supply contacts in an effort to increase the symmetry
of the potential distribution at zero magnetic field.

[0054] The sense contacts in both operating phases, i.e., contacts 23 and
24 in the first operating phase and contacts 21 and 22 in the second
operating phase, are "framed" by supply contacts having different
polarities. For example, the sense contact 24 during the first operating
phase is adjacent to the supply contact 22 having negative polarity and,
at the other side, adjacent to the supply contact 21 having positive
polarity. Moreover, the directions of the electric currents passing by
the sense contacts 23, 24 during the first operating phase are opposite
to each other. The magnetic field in the y-direction acts on the electric
current flowing in opposite directions in the different portions of the
Hall effect region in an opposite manner: pushing the current streamlines
towards the surface of the Hall effect region 11 near the sense contact
24 and pulling away the current streamlines from the surface of the Hall
effect region 11 near the sense contact 23, or vice versa. This leads to
a relatively pronounced difference in the electric potentials measured at
the sense contacts 23, 24 and thus to a relatively high differential
voltage that can be sensed or measured by the sense element 91. The
situation is similar during the second operating phase with respect to
the contacts 21 and 22 functioning as sense contacts during the second
operating phase.

[0055] FIG. 1c shows a plan view of a vertical Hall sensor according to
another embodiment of the disclosed teachings. In this embodiment, more
"inner" contacts are used, so that the percentage of outer contacts is
reduced. The vertical Hall sensor shown in FIG. 1c comprises the Hall
effect region 11, in or on the surface of which 21 identical contacts
numbered from 1 to 21 from left to right are arranged on a regular grid
along the x-axis in order to measure the magnetic field in the
y-direction By. The upper half of FIG. 1c shows the vertical Hall sensor
in its configuration for the first operating phase of the spinning
current scheme and the bottom half of FIG. 1c shows the same vertical
Hall effect sensor in its configuration for the second operating phase.

[0056] During the first operating phase the contacts 31, 21-1, 21-2, 21-3,
and 21-4 function as positive supply contacts (indicated by the solid
black filling) and are connected to a positive terminal of the voltage
supply 81. The contacts 22-1, 22-2, 22-3, 22-4, and 32 are configured to
function as negative supply contacts during the first operating phase
(indicated by the solid white filling) and are connected to a negative
terminal of the voltage supply 81. A first group of sense contacts
comprises the contacts 23-1 to 23-4 (dark, upward hatching). Each of the
sense contacts 23-1 to 23-4 is framed by a negative supply contact 22-i
on the left and a positive supply contact 21-i on the right. The sense
contacts 23-1 to 23-4 are connected to two sense elements of a plurality
of sense elements V1 to V8. For example, the sense contact 23-1 is
connected to a second input of a sense element V1 and a first input of a
sense element V2. A second group of sense contacts comprises the contact
24-1 to 24-5 (light, downward hatching), each of which is connected to
one or two of the eight sense elements V1 to V8. Each one of the sense
contacts 24-1 to 24-5 is framed by a positive supply contact 31 or
24-(i-1) on the left and a negative supply contact 22-i or 32 at the
right.

[0057] The vertical Hall sensor also comprises two floating contacts 63-1
and 63-5 as the outmost contacts, i.e., having the ordinal numbers 1 and
21, respectively.

[0058] The contacts having ordinal numbers from #3 to #19 are spinning
current contacts which means that each one of the spinning current
contacts functions as a supply contact during the first operating phase
and a sense contact during a second operating phase, or vice versa.
Furthermore, the spinning current contacts are arranged along a central
portion of the Hall effect region. More precisely, the entire plurality
of contacts numbered 1 through 21 is arranged in a sequence along a path
extending between a first end (e.g., the left end) and a second end
(e.g., the right end) of the Hall effect region 11. In the configurations
shown in FIGS. 1b and 1c the path is not explicitly depicted in the
figures, but it can be derived from the arrangement of the contacts that
the path is straight or rectilinear in both cases. In general, the path
may have other forms as well, such as curved, angled, polygonal, or
piece-wise straight. In the vertical Hall sensor shown as a schematic
plan view in FIG. 1c the central portion extends from between the
contacts having ordinal numbers #2 and #3 to somewhere between the
contacts with the ordinal numbers #19 and #20.

[0059] During the second operating phase the spinning current contacts
have changed their respective functions so that former supply contacts
21-i, 22-i now function as sense contact and former sense contacts 23-i,
24-i function as supply contacts.

[0060] The contacts 31 and 32 are supply-only contacts that function as
supply contacts during the first operating phase, but are left floating
during the second operating phase. The spinning current scheme is applied
or extended to the supply-only contacts 31, 32 during the first operating
phase, but it is not applied to these contacts during the second
operating phase. If the spinning current scheme would be applied to the
supply-only contacts 31, 32 during the second operating phase, the
supply-only contact 31 would have to act as a sense contact of the first
group and the supply-only contact 32 would have to function as a sense
contact of the second group mentioned above. As the supply-only contacts
31, 32 are relatively close to the first and second ends of the Hall
effect region 11, respectively, the current distribution may be notably
asymmetric in the vicinity of the supply-only contacts 31, 32, which is
likely to degrade a performance of the vertical Hall sensor with respect
to reducing the zero-point error as much as possible.

[0061] During the second operating phase, seven sense elements V9 to V15
are used in order to sense seven differential voltages between pairs of
sense contacts. On the basis of the differential voltages sensed or
measured by the sense elements V1 to V8 during the first operating phase
and of the sense elements V9 to V15 during the second operating phase, an
output signal of the vertical Hall sensor may be determined, for example,
by means of a linear combination of the various differential voltages.

[0062] As an option, the floating contacts 63-1 and 63-5 may be used as
supply-only contacts during the second operating phase, as indicated in
the bottom half of FIG. 1c by the dashed lines, in order to further
improve the symmetry of the current distribution during the second
operating phase. In this case, the vertical Hall sensor would comprise
four supply-only contacts, 63-1, 31, 32, and 63-5 (having the ordinal
numbers #1, #2, #20, and #21, respectively). The four supply-only
contacts comprise two outermost supply-only contacts which may be spaced
apart from the first and the second end by a distance greater than a
maximal spacing of the at least four spinning current contacts.

[0063] The operation of the vertical Hall sensor shown in FIG. 1c may be
summarized as follows (the contacts will be referred to by means of their
ordinal numbers). In the first operating phase, the electric current
flows from contact #2 to #4, #6 to #4, #6 to #8, #10 to #8, #10 to #12,
#14 to #12, #14 to #16, #18 to #16, #18 to #20. The voltages are tapped
at the contacts in between the supply contacts whereby the potential at
contacts #5, #9, #13, #17 goes up (under the action of a particular By
field) wherein the potential at the contacts #3, #7, #11, #15, and #19
goes down. The eight sense elements or voltmeters V1 . . . V8 may be used
to measure these signals differentially.

[0064] In the second operating phase the current flows from contacts #3 to
#5, #7 to #5, #7 to #9, #11 to #9, #11 to #13, #15 to #13, #15 to #17,
#19 to #17. The voltages are again tapped at the contacts in between
these supply contacts. Whenever the potentials in the first operating
phase at contacts #5, #9, #13, #17 increase due to a By field, the
potentials in the second operating phase at contacts #6, #10, #14, #18
also increase while the potentials in operating phase 2 at contacts #4,
#8, #12, #16 decrease. One may measure these potentials with the seven
sense elements or voltmeters V9 . . . V15.

[0065] Note that we can regard the device reaching from contact #3 to
contact #5 in the second operating phase as a basic building block, whose
mirror counterpart is placed to its right, then again mirrored at the
right edge and placed to the right, then again mirrored at the right
edge, etc. Therefore, the current consumption of a long strip as the Hall
effect region increases, because several current paths are connected in
parallel. As a countermeasure, the width (i.e., the extension of the
contacts and the Hall effect region 11 in y-direction) may be kept small.
Anyhow, several devices are typically connected in parallel in order to
reduce the resistance and the noise of the output signal. Three options
may be considered: (i) use several devices in several Hall effect regions
and connect them in parallel by wires, (ii) use a wider Hall effect
region 11 and wider contact strips to reduce the internal resistance, and
(iii) use a longer strip with more contacts with a narrow Hall effect
region and narrow contacts. From these three options number (iii) is
typically desired in one embodiment, because the influence of the
asymmetries at the right and left edges are more strongly reduced than
with the other solutions. Usually, the spacing of the contact scales with
the depth (i.e., the extension into the drawing plane in FIG. 1c) of the
Hall effect region. The depth is in the order of 5 μm in modern CMOS
processes, such as 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm,
8 μm, or 9 μm. Therefore, the spacing of the contacts is similar
(+/-1 μm or +/-2 μm). Thus, a device with 21 contacts may be about
130 μm long in one embodiment (or more generally between 50 μm and
250 μm, depending on the contact spacing) which is acceptable for most
applications.

[0066] In FIG. 1c, separate voltmeters V1 to V15 are depicted that are
used to measure the output voltages of neighboring cells or basic
building blocks. Two neighboring voltages can be subtracted and all these
terms can be summed up to get the total signal per operating phase. In
general, a linear combination of the readings of the voltmeters V1 to V8
and of the voltmeters V9 to V15 may be used. As another option it is also
possible to compute the average of the outputs of the voltmeters V1 to V8
and also the average of the outputs of the voltmeters V9 to V15. This may
be done by hardware when contacts #3, #7, #11, #15, #19 are tied together
and contacts #5, #9, #13, #17 are tied together in the first operating
phase. The potential may then be measured between these two nodes. Doing
so may, however, result in reduced performance (meaning: larger residual
zero-point error), because due to mismatch there will typically be
current flowing between the output port and this leads to larger
zero-point errors. One elegant way to compute the average of all output
voltages in an isolated way is to split up the large MOSFETs of the
differential input pair of a pre-amplifier (i.e., the first amplifier
connected to the outputs of the Hall devices) and to connect the
voltmeter V1 to the first part of it, the voltmeter V2 to the second, the
voltmeter V3 to the third, etc. This method reduces the noise, but does
not increase the signal.

[0067]FIG. 1D shows a schematic top view of a vertical Hall sensor with
seven identical contacts numbered 1 to 7 in the Hall effect region 11
arranged on a regular grid along the x-axis in order to measure By
fields. During the first operating phase the contacts 21-1 and 21-2 (#1
and #5, respectively) are configured to function as positive supply
contacts. The contacts 22-1 and 22-2 (#2 and #7, respectively) are
configured to function as negative supply contacts during the first
operating phase. The sense contact 23, (#4) is substantially located in
the middle of the Hall effect region 11 and is connected to a positive
input of a first sense element V1 and a negative input of a second sense
element V2. Two other sense contacts 24-1 and 24-2 are also connected to
the first and second sense elements V1, V2. The supply contacts 21-1,
21-2, 22-1, and 22-2 are connected to one or two voltage supplies of the
voltage supplies 81, 82, 83.

[0068] In the second operating phase only two voltage supplies 81, 82 are
used to supply electric energy to the vertical Hall sensor. All seven
contacts of the vertical Hall sensor are spinning current contacts so
that the former supply contacts 21-1, 22-1, 21-2, and 22-2 function as
sense contacts during the second operating phase. The contacts 23, 24-1
and 24-2 function as supply contacts and are thus connected to the
voltage supplies 81, 82 in the manner depicted in FIG. 1D. A first
differential voltage may be tapped between the contacts 22-1 and 21-2 by
means of the sense element or voltmeter V1. A second differential voltage
may be tapped as a second sense signal between the sense contacts 21-1
and 22-2 by means of the sense element or voltmeter V2. Note that the two
sense elements V1 and V2 tap their respective differential voltages in a
nested manner with respect to the sequence of the seven contacts.

[0069] The vertical Hall sensor shown in FIG. 1D has an odd number of
contacts (7 or 11 or 15; FIG. 1D illustrates a configuration having seven
contacts). The symmetry may be increased by using the outmost contacts
21-1 and 22-2 as supply (=input) contacts in the first operating phase
and as sense (=output) contacts in the second operating phase. Moreover,
they may have different polarity in both phases, as illustrated in FIG.
1d: in the first operating phase one of the outmost contacts is at
positive potential (contact 21-1 having ordinal number 1 in FIG. 1D)
while the other one is at negative potential (contact 22-2 having ordinal
number 7 in FIG. 1D). In the second operating phase one of the outputs
increases with an applied magnetic field By, whereas the other one
decreases (compare the contacts 21-1 (#1) and 22-2 (#7) in the second
operating phase in FIG. 1D). Note that in the second operating phase the
electric potential (without applied magnetic field) at contact 21-1 is
different from the electric potential at contact 22-1, yet the (common
mode) potentials at the contact 21-1 and 22-2 are identical and the
(common mode) potentials at 22-1 and 21-2 are also identical due to
symmetry. Therefore, the output signals may be measured between the
contacts 21-1 and 22-2, as well as between the contacts 22-1 and 21-2 and
subtract them in order to get a signal of the vertical Hall sensor during
a second operating phase. In the first operating phase the two measured
voltages between the contacts 24-1 and 23, as well as between the
contacts 23 and 24-2 are also subtracted to get a signal of the vertical
Hall sensor for the first operating phase. Averaging or low-pass
filtering the output signal of the vertical Hall sensor for the first
operating phase and the second operating phase yields a relatively
accurate measurement of the magnetic field in the y-direction with low
zero-point error or offset.

[0070] The vertical Hall sensor shown in FIG. 1D uses three voltage
supplies 81, 82, 83 in the first operating phase and only two voltage
supplies 81, 82 in the second operating phase. Two sense elements or
voltmeters V1 and V2 are used in both the first and the second operating
phase.

[0071] The principle illustrated in FIG. 1D can be generalized to more
than seven contacts: whenever the potential distribution is symmetric to
the center in at least one of the operating phases, the differential
voltages may be measured in a nested way as illustrated in FIG. 2. FIG. 2
shows three voltmeters V1, V2, and Vk of a plurality of k voltmeters,
which tap differential voltages along the Hall effect region in a nested
manner. The innermost voltmeter V1 is connected to the two innermost
sense contacts while the outermost voltmeter Vk is connected to the two
outmost sense contacts. In the configuration of FIG. 1D, bottom half, the
electric current flows from left to right between the two supply contacts
24-1 and 23, whereas the electric current flows from right to left
between the two supply contacts 24-2 and 23. This observation can also be
made for a vertical Hall sensor implementing the voltmeter configuration
shown in FIG. 2: the direction of electric current flow is opposite in
the vicinity of the two sense contacts that are connected to one of the k
voltmeters V1 to Vk. In summary, the at least four spinning current
contacts may comprise an odd number of spinning current contacts equal to
or greater than seven. During at least one operating phase of the
spinning current scheme an even number equal to or greater than four of
the spinning current contacts may be configured to function as sense
contacts. Differential sense signals may be tapped between pairs of the
spinning current contacts functioning as sense contacts during said
operating phase, wherein the pairs are arranged along the path in a
nested manner.

[0072] FIG. 3 shows the schematic plan view or top view of a vertical Hall
sensor with two Hall effect regions 11 and 11'. The entire vertical Hall
sensor comprises 18 substantially identical contacts of which contacts
with the ordinal numbers 1 to 9 are arranged in the first Hall effect
region 11 and contacts with the ordinal numbers 1' to 9' are arranged in
the second Hall effect region 11'. Within each of the Hall effect regions
11, 11' the contacts are arranged on a regular grid along the x-axis in
order to a measure magnetic field By in the y-direction. Hence, the
vertical Hall sensor may comprise two separate wells formed in a
substrate, each having nine contacts. The inputs of the first Hall effect
region are contacts 21 and 22 (#6 and #4, respectively) during the first
operating phase. The corresponding contacts at the second Hall effect
region 11', i.e. contacts 23' and 24' (#6' and #4', respectively) are
used as outputs of the second Hall effect region 11'. The outputs of the
first Hall effect region 11 are the contacts 23 and 24 (#7 and #5,
respectively), while the corresponding contacts 23' and 24' (#6' and #4',
respectively) of the second Hall effect region 11' are used as inputs.
Both output signals (between contacts #5 and #7, as well as between
contacts #4' and #6') are added to give a total output signal in the
first operating phase. In the second operating phase the output signals
between the contacts #4 and #6, as well as between #5' and #7' are added
to give the total output signal. The sum of both total output signals is
proportional to the magnetic field in the y-direction By with a greatly
reduced zero point error. Both Hall effect regions 11, 11' could be
connected at their leftmost and/or rightmost ends or edges.

[0073] The first Hall effect region 11 comprises five floating contacts.
Three contacts 64-1, 61, and 63 are arranged to the left of the region
where the spinning current contacts 21 to 24 are arranged (central
portion). Two other floating contacts 62 and 64-2 are arranged on the
right side of the spinning current contacts 21 to 24. The second Hall
effect region 11' has three floating contacts 62-1', 63', and 61' at the
left side of the spinning current contacts 21' to 24' and two floating
contacts 64', 62-2' on the right of the spinning current contacts 21' to
24'.

[0074] FIG. 4 shows a schematic top view or plan view of another vertical
Hall sensor with 18 substantially identical contacts. Nine of the
substantially identical contacts numbered from 1 to 9 are arranged on a
first Hall effect region 11 and the remaining nine of the substantially
identical contacts numbered 1' to 9' are arranged on the second Hall
effect region 11'. The nine contacts arranged on the same Hall effect
region 11 or 11' are arranged on a regular grid along the x-axis in order
to measure magnetic fields in the y-direction By. The vertical Hall
sensor shown in FIG. 4 uses cross-coupled outputs as follows: in the
first operating phase a first output voltage is measured between a sense
contact 23 of the first Hall effect region 11 and a sense contact 24' of
the second Hall effect region 11' by means of a sense element or
voltmeter V11, so that a voltage at the sense element V11 is equal to
V11=V5-V4', where V5 is the electric potential at the sense contact 23
(#5 in the sequence of the first Hall effect region 11) and V4' is the
electric potential at the sense contact 24' (#4' in the sequence of the
second Hall effect region 11'). A second output voltage is measured
between the sense contacts 24 (#7 in Hall effect region 11) and the sense
contact 23' (#6' for Hall effect region 11') by means of the sense
element or voltmeter V12 so that V12=V7-V6', wherein V7 designates the
electric potential at contact #7 of the first Hall effect region 11 and
V6' designates the electric potential at the contact #6' of the second
Hall effect region 11'. The total output voltage for the first operating
phase is computed as the difference of both: Sig1=V11-V12. Similarly, in
the second operating phase the first output voltage is measured between
contact 22 (#4) and contact 22' (#5') by means of a sense element or
voltmeter V21 with a differential voltage V21=V4-V5', wherein V4 is the
electric potential measured at the sense contact 22 of the first Hall
effect region 11 and V5' is the electric potential at the sense contact
22' of the second Hall effect region 11'. A second output voltage is
measured between the sense contacts 21 and 21' by means of a sense
element or voltmeter V22 as a differential voltage V22=V6-V7', wherein V6
is the electric potential at the sense contact 21 (#6 in Hall effect
region 11) and V7' is the electric potential at the sense contact 21'
(#7' in the second Hall effect region 11'). A total output voltage is
computed as the difference of both: Sig2=V21-V22. The difference of both
total output voltages is Sig1-Sig2=V11-V12-V21+V22 and is proportional to
the magnetic field in the y-direction By with greatly reduced zero-point
error.

[0075] Three floating contacts 63-1, 61, and 64 are arranged to the left
of the spinning current contacts 21 to 24 in or on the surface of the
first Hall effect region 11. Two further floating contacts 62 and 63-2
are arranged to the right of the spinning current contacts 21 to 24.
Regarding the second Hall effect region, three floating contacts 62-1',
63', and 61' are arranged to the left of the spinning current contacts
21' to 24' and two floating contacts 64', 62-3' are arranged to the right
thereof.

[0076] FIG. 5 shows a schematic top view or plan view of a vertical Hall
sensor according to an embodiment of the teachings disclosed herein. The
vertical Hall sensor comprises 16 substantially identical contacts, eight
of which are arranged in or on the surface of the first Hall effect
region 11 and the remaining eight contacts are arranged in or on the
surface of the second Hall effect region 11'. In or on the surface of the
first and second Hall effect regions 11, 11' the corresponding contacts
are arranged on a regular grid along the x-axis in order to measure
magnetic fields in the y-direction By. The configuration of the vertical
Hall sensor shown in FIG. 5 uses cross-coupled outputs of the first and
second Hall effect regions 11, 11'.

[0077] For the first Hall effect region 11 the spinning current contacts
are the contacts having ordinal numbers between 2 and 7 and for the
second Hall effect region 11' the spinning current contacts are the
contacts having ordinal numbers between 2' and 7'. The outmost contacts
in or on each Hall effect region 11, 11' are supply-only contacts. In
particular, the first Hall effect region 11 has a supply-only contact 31
which is connected to a positive pole of the voltage supply during the
first operating phase of the spinning current scheme. A second
supply-only contact 33 formed in or on the first Hall effect region 11 is
left floating during the first operating phase. With respect to the
second Hall effect region 11' a supply-only contact 32' is connected to a
negative pole of the voltage supply during the first operating phase. The
other supply-only contact 34' is left floating during the first operating
phase.

[0078] During the second operating phase the supply-only contact 31 of the
first Hall effect region 11 is left floating, while the other supply-only
contact 33 of the first Hall effect region 11 is now connected to the
negative pole of a voltage supply and thus functions as a supply contact.
The left supply-only contact 32' of the second Hall effect region 11' is
also left floating during the second operating phase, whereas the right
supply-only contact 34' of the second Hall effect region 11' is connected
to a positive pole of a voltage supply, i.e., the supply-only contact 34'
functions as a supply contact during the second operating phase.

[0079] Regarding the symmetry of the vertical Hall sensor, the contacts
having ordinal numerals 8 and 8' are floating while the leftmost contacts
with ordinal numbers 1 and 1' are at reference and supply potential,
respectively, during the first operating phase. During the second
operating phase the contacts with ordinal numbers 1 and 1' are floating
while the rightmost contacts are at reference and supply potentials,
respectively. In one embodiment, the spacing in y-direction between the
first and the second Hall effect regions, 11, 11' is small (e.g., <10
μm). The spacing depends on the application: if the application has
homogeneous fields, the spacing can also be larger and, for example, a
conventional Hall plate for measuring magnetic field components
perpendicular to the surface of the Hall effect regions 11, 11' could be
inserted in between the first and second Hall effect regions 11, 11'.

[0080] Three differential voltages are tapped in a Hall effect
region-spanning manner during the first operating phase. A first
differential voltage V11 is tapped between the contacts 23-1 and 24-1' by
means of a corresponding sense element or voltmeter. A second
differential signal V12 is tapped between the contacts 24 and 23'. A
third differential voltage V13 is tapped between the sense contacts 23-2
and 24-2'. During the second operating phase three further differential
voltages V21, V22, and V23 are tapped in a Hall effect region-spanning
manner. The six differential voltages measured during the first and the
second operating phase may be processed in a similar manner to what has
been explained in connection with FIG. 4. In particular a linear
combination of the differential voltages V11 to V23 may be determined.

[0081] When examining the contact configurations of the first and second
Hall effect regions 11, 11' it can be seen that the functions of the
various electrodes numbered 1' to 8' of the second Hall effect region 11'
are substantially complementary to the functions of the corresponding
contacts numbered 1 to 8 of the first Hall effect region 11. For example,
the contact having the ordinal number 1 in the sequence of the first Hall
effect region 11 functions as a positive supply contact during the first
operating phase, while its counterpart having the ordinal number 1' in
the second Hall effect region 11' functions as a negative supply contact
during the first operating phase. Similar observations can be made for
the remaining contacts 2 to 8 and their corresponding contacts 2' to 8'.
The contacts of the first Hall effect region 11 and the contacts of the
second Hall effect region 11' are also complementary to each other during
the second operating phase.

[0082] In order to summarize the embodiment of the vertical Hall sensor
shown in FIG. 5: The vertical Hall sensor may further comprise a further
Hall effect region 11' in, or on a surface of which, is formed a further
plurality of contacts similar to the plurality of contacts formed in or
on the surface of the Hall effect region 11. The further plurality of
contacts is configured to function in a complementary manner to the
plurality of contacts. During each operating phase of the spinning
current scheme at least one first sensor signal is tapped between at
least two of the spinning current contacts of the plurality of contacts
formed in or on the surface of the Hall effect region and at least one
second sense signal is tapped between at least two spinning current
contacts of the further plurality of contacts formed in or on the surface
of the further Hall effect region, and wherein the at least one first
sense signal and the at least one second sense signal are added or
subtracted from each other by an output signal determiner of the vertical
Hall sensor. The further Hall effect region 11' is substantially parallel
to the Hall effect region 11. The spinning current contacts of the Hall
effect region 11 and the further Hall effect region 11' between which the
sense signal is tapped have a corresponding position within the plurality
of contacts and the further plurality of contacts, respectively. A
plurality of the spinning current contacts functioning as supply contacts
and of the supply-only contact is inversed between the Hall effect region
11 and the further Hall effect region 11' for a particular operating
phase of the spinning current scheme (i.e., contacts at corresponding
positions in the Hall effect region 11 and the further Hall effect region
11' have opposite electric polarities), so that directions of electrical
current flow are opposite to each other in corresponding portions of the
Hall effect region and the further Hall effect region.

[0083] FIG. 6 shows schematic plan views of a vertical Hall sensor during
a first operating phase and a second operating phase. The vertical Hall
sensor comprises a single Hall effect region 11 and a plurality of 20
substantially identical contacts. The 20 substantially identical contacts
are arranged along a straight line or path (coinciding with the x-axis)
in an evenly spaced manner. The contacts are numbered in a rising order
of their x-coordinates in a same manner as elsewhere within the
description of the other figures herein. The 20 substantially identical
contacts are spinning current contacts and they are configured to
alternatingly function as supply contacts and sense contacts according to
a spinning current scheme. Every fourth contact is shorted: thus, contact
21-1 (#1) is shorted to contact 21-2 (#5), 21-3 (#9), 21-4 (#13), and
21-5 (#17), resulting in a single node N1 (dotted line in FIG. 6). In a
similar manner the contacts 22-1 to 22-5 having ordinal numerals #3, #7,
#11, #15, and #19 are shorted (dashed line) resulting in a single node
N3. Shorting the contacts 23-1 to 23-5 (widely dash-dotted line) results
in a single node N4. Finally, the contacts 24-1 to 24-5 (ordinal numerals
#2, #6, #10, #14, and #18) are shorted (narrowly dash-dotted line) which
results in a single node N2. Shorting the various spinning current
contacts thus gives four nodes N1, N2, N3, N4. In a first operating phase
electrical power is supplied between nodes N1 and N3 and the signal is
tapped between N2 and N4. In a second operating phase electrical power is
supplied between nodes N2 and N4 and the signal is tapped between N1 and
N3. There is no need for switches or other electronic devices to short
the contact 21-1 to 21-5 to the node N1; this is done merely via a low
ohmic conductor like aluminum wires or strips on the die. In this manner
it may be avoided that switches add resistances that are different in the
first and second operating phases, as this could give rise to errors in
the spinning current technique.

[0084] The idea behind the vertical Hall sensor as shown in FIG. 6 is the
following: there are several Hall devices in parallel: the first Hall
device comprises contacts 21-1 (#1), 24-1 (#2), and 22-1 (#3). Using only
the ordinal numbers to designate the contacts, the second Hall device
comprises the contacts #3, #4, and #5. The third Hall device comprises
the contacts #5, #6, and #7, etc. Finally, a ninth Hall device comprises
the contacts #17, #18, and #19. Each Hall device has an individual
stochastic offset (zero-point error). The connection of contacts
effectively is a parallel circuit of all these devices. The total current
splits up into nine substantial equal parts, each one flowing through one
of the nine Hall devices. The outputs are also connected in parallel:
this produces an average of all outputs. In particular, it produces an
average of the total offset error: the mean total offset error is sqrt(9)
times smaller than the offset of a single device.

[0085] Moreover, the parallel circuit of an odd number of individual Hall
devices makes the total device more symmetric: in the first operating
phase the positive supply contact 21-1 (#1) is close to one end of the
Hall effect region 11, while a sense contact 23-5 (#20) is close to the
opposite end of the Hall effect region 11. In the second operating phase
we have similar conditions: the positive supply contact 23-5 (#20) is
close to one end of the Hall effect region 11, while a sense contact 21-1
(#1) is close to the other end of the Hall effect region 11. Hence, the
unavoidable asymmetries at the end of the Hall effect region(s) are
substantially identical in both operating phases: consequently, they are
likely to cancel almost completely if the signals of the first and the
second operating phases are added/subtracted.

[0086] Furthermore, there is substantially no asymmetry between the first
and the second operating phases for the inner contact, just the (near
perfect) exchange of supply contacts with sense contacts which gives a
highly accurate spinning current technique.

[0087] Note that the current consumption increases by a factor of 9
compared with a single device. On the other hand, the noise decreases due
to the very same fact. The current drain can be kept at a minimum if the
contacts are small and the width of the contacts and of the Hall effect
region(s) in y-direction are small.

[0088] FIG. 7 shows schematic plan views of a vertical Hall sensor
according to an embodiment of the teachings disclosed herein in a
configuration for a first operating phase (top) and a configuration for a
second operating phase (bottom). The vertical Hall sensor shown in FIG. 7
is derived from the vertical Hall sensor shown in FIG. 6.

[0089] The vertical Hall sensor shown in FIG. 7 comprises 24 substantially
identical contacts that are arranged in or on the surface of the Hall
effect region 11. Spinning current contacts are arranged in a central
portion of a path extending between a first end (e.g., the left end) and
a second end (e.g., the right end) of the Hall effect region 11, along
which the plurality of contacts is arranged. The central portion
substantially begins to the left of the spinning current contact 21-1 and
ends substantially to the right of the spinning current contact 23-5. Two
supply-only contacts 32, 33 are arranged to the left of the central
portion and two other supply-only contacts 31, 34 are arranged to the
right of the central portion. Each spinning current contact within the
central portion is connected to one of four nodes N1, N2, N3, and N4,
depending on its position in the sequence of the contacts. Reference is
made to the description of FIG. 6 regarding this aspect. Each supply-only
contact is connected to one of the nodes N1 to N4 via one of four
switches SW1, SW2, SW3, and SW4. The supply-only contact 32 is connected
via switch SW1 to the node N3. The supply-only contact 33 is connected
via the switch SW2 to the node N4. The supply-only contact 31 is
connected via the switch SW3 to the node N3. The supply-only contact 34
is connected via the switch SW4 to the node N2.

[0090] During the first operating phase, the supply-only contact 32 acts
as a negative supply contact because the switch SW1 is closed and
connected to the negative pole of the voltage supply 81. The supply-only
contact 33 is left floating because the switch SW2 is open during the
first operating phase. The supply-only contact 33 functions as a positive
supply contact because the switch SW3 is closed so that a connection is
made to the positive contact of the voltage supply 81. The supply-only
contact 34 is left floating because the switch SW4 is open during the
first operating phase.

[0091] When passing from the first operating phase to the second operating
phase, the states of the switches S1 to S4 are toggled, i.e., switches
SW1 and SW3 are open while the switches SW2 and SW4 are closed.
Accordingly, the supply-only contacts 32 and 31 are floating during the
second operating phase. The supply-only contact 33 functions as a
positive supply contact because due to the closed switch SW2 the
supply-only contact 33 is connected to the node N4 and thus to the
positive pole of the voltage supply 81. The supply-only contact 34
functions as a negative supply contact during the second operating phase
because the switch SW4 is closed so that the supply-only contact 34 is
connected to the node N2 and the negative pole of the voltage supply 81.

[0092] The embodiment of the vertical Hall sensor shown in FIG. 7 has a
higher symmetry than the vertical Hall sensor shown in FIG. 6. The higher
symmetry comes, however, at the expense of slightly increased current
consumption: with the four switches SW1 to SW4 one supply contact is
added at the left and the right of the central portion, i.e., the
spinning current contact, to prolong the range of potential symmetry at
both ends of the Hall effect region 11.

[0093] FIGS. 8 and 9 show vertical Hall sensors having Hall effect regions
11 that are not straight. As a consequence, the paths that extend between
a first end and a second end of the Hall effect region and along which
the plurality of contacts is arranged, are not straight, either.

[0094]FIG. 8 shows a vertical Hall sensor in which the Hall effect region
11 has an L-shape. The vertical Hall sensor comprises 16 contacts, eight
of which are formed in or on the surface of a portion of the Hall effect
region 11 extending in the x-direction, and the remaining eight contacts
are formed in or on the surface of a portion extending in the
y-direction. Contacts having equal functions during a given operating
phase of the spinning current scheme are mutually connected, thus forming
a node. Typically, a spinning current contact may fulfill one of the
following four functions: positive supply contact, negative supply
contact, "positive" sense contact, and "negative" sense contact. The
spinning current contacts 22-1 to 22-4 function as negative supply
contacts during the first operating phase and are connected to the node
N1. The spinning current contacts 23-1 to 23-4 function as positive sense
contacts during the first operating phase and are connected to the node
N2. The spinning current contacts 21-2 to 21-4 function as positive
supply contacts during the first operating phase and are connected to the
node N3. The spinning current contacts 24-1 to 24-4 function as negative
sense contacts during the first operating phase and are connected to the
node N4.

[0095] As with other vertical Hall sensors disclosed herein, the contacts
are substantially identical. Furthermore, the contacts are arranged in an
equidistant manner along a polygon curve, here the L-shape. An exception
of the equidistant spacing between two adjacent contacts of the plurality
of contacts is the distance between the two innermost contacts 24-2 and
22-3.

[0096]FIG. 9 shows another logical Hall sensor that also comprises 16
substantially identical contacts formed in or on the surface of a Hall
effect region 11. The Hall effect region 11 is arc-shaped. The path
extending between the first end and the second end of the Hall effect
region 11 is also arc-shaped, i.e. a smooth curve. Other possible
configurations of the Hall effect region 11 and the path could comprise
piece-wise straight curves. Although not explicitly depicted in FIG. 9,
the various spinning current contact may be mutually connected to each
other in a similar manner as shown in FIG. 8. The spinning current
contacts have an equidistant spacing along the path.

[0097] FIG. 10 shows a schematic top view or plan view of a vertical Hall
sensor according to an embodiment of the teachings disclosed herein. The
vertical Hall sensor shown in FIG. 7 may be regarded as a predecessor for
the embodiment shown in FIG. 10. The spinning current contacts 21-i,
22-i, 23-i, and 24-i are referred to as first type contacts in the
context of the description of FIG. 10 and FIG. 11. The supply-only
contacts 31 to 33 are also referred to as first type contacts. Between
these contacts of the first type, which are connected to the nodes N1 to
N4, additional contacts 65 may be inserted. These contacts of a second
type are typically located in a symmetric manner between the contacts of
the first type. One or several of the second type contacts 65 may be
situated between each two contacts of the first type. The second type
contact 65 may have another shape or form than the first type contact: in
the embodiment of FIG. 10 the second type contacts 65 are only half as
wide as the first type contacts. An effect of the second type contacts 65
as they are shown in FIG. 10 is that they pull the current flow towards a
middle line 68 of the Hall effect region 11. Furthermore, they pull the
current flow towards the surface of the Hall effect region 11, i.e., they
prevent that the current flows too much into the depth. This may be
important for cases in which a semiconductor manufacturing process forms
a highly conductive buried layer, such as an n+ doped buried layer (nBL)
which could pull the current towards the depth and cause a short-circuit.
The first aspect of pulling the current flow towards the middle line 68
of the Hall effect region may be important when it is not possible that
the contacts of the first type, i.e., the spinning current contacts,
extend over the entire width of the Hall effect region: in this case, the
magnetic sensitivity is reduced due to components of the currents that
flow in the y-direction. In order to reduce/prevent these current
components, the second type contacts 65 are arranged close to the middle
line 68, which pull the current towards the middle.

[0098] As shown in FIG. 11, the second type contacts or floating contacts
65 may also be connected to each other in a similar manner as the first
type contacts. FIG. 11 shows a schematic plan view of a vertical Hall
device according to an embodiment of the teachings disclosed herein
during the first operating phase. Second type contacts that are to the
right of a negative supply contact have the reference signs 61-1 to 61-6.
Second type contacts that are to the right of a positive sense contact
have the reference signs 62-1 to 62-6. Second type contacts that are to
the right of the positive supply contacts have the reference signs 63-1
to 63-6. Second type contacts that are to the right of negative sense
contacts have the reference signs 64-1 to 64-6. The second type contacts
with the reference signs 61-1 to 61-6 are connected to each other and
thus form one floating node. The remaining second type contacts are also
connected to each other in groups, thus forming three other floating
nodes. By connecting a second type contact to other second type contacts
the individual second type contacts are actually not floating anymore in
the sense of a single contact. Nevertheless, the connected second type
contacts are floating as a network node because they are not externally
connected to other circuit elements. The nodes N1 to N4 connecting the
spinning current contacts have been omitted from illustration in FIG. 11
for the sake of clarity.

[0099] In both FIGS. 10 and 11 the Hall effect region 11 is elongated and
may be a tub formed in a substrate. On the surface of the Hall effect
region 11 contacts of the first and second types may be placed so that
between each two contacts of the first type there are M contacts of the
second type (M=1 is possible, as well). All contacts are numbered along
the Hall effect region 11 in ascending order. The contacts 1, 1+4*(1+M),
1+2*4*(1+M), . . . 1+N*4*(1+M) are connected with the node N1. The
contacts 2+M, 2+M+4*(1+M), 2+M+2*4*(1+M), . . . , 2+M+N*4*(1+M) are
connected with the node N2. The contacts 3+2*M, 3+2*M+4*(1+M),
3+2*M+2*4*(1+M), . . . , 3+2*M+N*4*(1+M) are connected with the node N3.
Finally, the contacts 4+3*M, 4+3*M+4*(1+M), 4+3*M+2*4*(1+M), . . . ,
4+3*M+N*4*(1+M) are connected with the node N4.

[0100] Typically, the number of first-type contacts is at least eight. In
the alternative, the number could be 12 or 16, which is expected to lead
to a better performance of the vertical Hall sensor, in particular with
respect to a reduction of the zero-point error.

[0101] As shown in FIGS. 8 and 9, the Hall effect region does not
necessarily have to be straight, i.e., the contacts do not necessarily
have to be arranged along a straight line or path. The Hall effect region
11 simply has to be elongated and its longitudinal direction may be a
smooth curve (a segment of a circle or an ellipse or it may have a
L-shape (or a polygon section). The contacts may then be arranged in a
sequence along this curve.

[0102] The connection of individual contacts to a node may be hard-wired
which means that in the operating phases of the spinning current scheme
the connections do not have to be changed (it does not necessarily have
to be a fixed wiring by means of a conductor, but it could also be an
electronic element such as a MOS switch which, however, must not be
opened in one operating phase and closed in another operating phase).

[0103] Typically, the number of the first type contacts is an even number.

[0104] In the following FIGS. 12a to 14b several vertical Hall sensors are
introduced which achieve a high degree of symmetry by means of a
ring-shaped Hall effect region. In particular, the contacts of the
vertical Hall sensors shown in FIGS. 12a to 14b are highly symmetric to
each other, because a ring has no start and no end. Therefore, no
distinction has to be made within the plurality of contacts as to which
contacts count as "inner" contacts and which count as "outer" contacts.
Boundary effects affecting the function of the contacts, for example with
respect to a distribution of an electric current or an electric potential
within the Hall effect region, are substantially the same for all
contacts.

[0105]FIG. 12A shows a schematic layout or plan view of a ring-shaped
vertical Hall element 100. The ring-shaped vertical Hall element 100 may
be formed in a substrate 101 that may be, for example, a p-doped
semiconductor or an isolating material. A ring-shaped tub or well 103 is
formed within the substrate 101, for example by n-doping the substrate
101 at locations where the ring-shaped tub 103 is to be formed. The
ring-shaped tub has a 90° symmetry referred to a center 105 of the
ring-shaped tub 103. As an alternative, the ring-shaped tub 103 could
have a higher symmetry (e.g., octagonal or circular shapes). Four
contacts 102a, 102b, 102c, 102d are formed in or on a surface of a
ring-shaped tub 103. By means of the four contacts 102a to 102d electric
connections can be made to the tub 103 at various locations thereof. The
four contacts 102a to 102d essentially extend from an inner perimeter
104a to an outer perimeter 104b of the ring-shaped tub 103.

[0106] The surface of the substrate 101 is parallel to the xy-plane. The
ring-shaped vertical Hall element 100 is typically indicative of magnetic
field components parallel to the xy-plane. Magnetic field components
parallel to the z-direction should not have significant influence on the
output signal of the device 100.

[0107] The device 100 is shown to have two portions of the ring parallel
to the x-axis and two portions of the ring parallel to the y-axis. Other
ring-shaped vertical Hall elements may be rotated by an arbitrary angle
around the symmetry center 105. For example, another ring-shaped vertical
Hall device 100 may have portions of the ring at +/-45° to the
x-axis and y-axis.

[0108] The four contacts 102a to 102d may be configured as spinning
current contacts with the contacts 102a and 102c being supply contacts
and the two other contacts 102b and 102d being sense contacts during the
first operating phase of the spinning current scheme, for example.

[0109]FIG. 12B shows a schematic cross-section of the device along the
x-axis and through the contacts 102b and 102c. It can be seen that the
contacts 102c and 102b are formed in a surface 106a of the tub 103 and
are shallower than the tub 103. As the device 100 is symmetric, the same
holds for the two other contacts 102a and 102d which cannot be seen in
FIG. 12B. In order to give an idea of the dimensions involved, the
following information is provided: the tub 103 may be about 5 μm thick
in the z-direction, whereas the contacts 102a to 102d are typically less
than 1 μm thick (preferably 0.2 μm thick) in one embodiment. Other
possible dimensions are, for example: tub thickness of 2 μm, 3 μm,
4 μm, 6 μm, 7 μm, or 8 μm and contact thickness of 0.05
μm, 0.1 μm, 0.5 μm, or 0.8 μm. The tub 103 may be lightly
n-doped with a dose of 1015 cm-3 to 1017 cm-3 whereas
the contacts 102a to 102d may be strongly n-doped with a dose of more
than 1017 cm-3 (e.g. 1019 cm-3). The tub 103 may be
identical to an n-epitaxial layer of current CMOS processes, where the
contacts 102a to 102d may be identical to shallow n.sup.+ S/D
source-drain contacts. The contacts may be reinforced by additional
n-CMOS wells. At a bottom 106b of the tub 103 there may be a buried layer
107 as is the case for robust BiCMOS/CMOS processes, but this is not
necessarily so. In case of an epitaxial layer it is often the case that
trenches isolate the epitaxial layer and the tub 103 laterally from the
substrate 101 (these trenches are not shown in FIGS. 12a to 12c).

[0110]FIG. 12c shows a schematic cross-section of the device along the
x-axis and through the center point or symmetry center 105 of the device.
The two portions of the tub 103 extending in the y-direction can be seen
in this cross-section. During operation, an electric current flows
through these portions in the y-direction, i.e., perpendicular to the
drawing plane. The total section of each portion is the width of the
portion times the depth of the tub 103. The width is equal to the
distance between the inner perimeter 104a and the outer perimeter 104b of
the ring-shaped tub 103. However, when the optional n-buried layer 107 is
present, a significant portion of the electric current is likely to flow
within the n-buried layer 107.

[0111] FIG. 13a shows a schematic layout or plan view of a ring-shaped
vertical Hall device 200. FIG. 13a also shows schematically how it is
connected in a circuit. Two diagonally opposite contacts 202b and 202d
are connected to an electric supply 220. The electric supply can be a
current or a voltage source; a current source 220 is shown in FIG. 13a.
At the other two diagonally opposite contacts 202a and 202c the output
signal 222a is measured. The output signal 222a can be the output voltage
measured with a high-impedance volt meter 221. As an alternative, an
output current could be measured by means of a low-impedance ampere
meter.

[0112] In cases in which no magnetic field is present, the output voltage
would ideally be 0: half the current flows between the contacts 202b and
202d over the right branch of the ring that contains the contact 202a,
whereas the other half of the current flows between the contacts 202b and
202d over the left branch of the ring that contains the contacts 202c. In
practice the output voltage is usually different from 0 due to
unavoidable asymmetries in the geometry or in the connectivity of the
device 200.

[0113] If there is a magnetic field component Bx< >0 while By=0,
this field acts on the charge carriers flowing through branches 203cd and
203ab. If there is a magnetic field component By< >0 while Bx=0,
this field acts on the charge carriers flowing through branches 203ad and
203bc.

[0114] Suppose Bx>0 and By=0: if the current flows into the contact
202d and out of the contact 202b, then the electrons in the tubs 203ab
and 203cd mainly flow in positive y-direction. Strictly speaking, the
electrons flow in semi-arcs because they enter the tub at the contact
202b and flow simultaneously into the depth (=negative z-direction=into
the drawing plane) of the tub 203ab and toward the contact 202a. After
approximately half of the length of the tub portion 203ab, the electrons
flow up toward the surface where the contact 202a is (=in positive
z-direction=out of the drawing plane). Due to the Lorentz-Force of the
Bx-fields on the electrons, they are pulled towards the surface of the
tub (106a in FIGS. 12b, 12c). This is due to the Hall effect: the Hall
effect pulls the electrons on smaller, shallower semi-arcs. This happens
in both tubs 203ab and 203cd. Consequently, the electric potential at the
contact 202a is lowered, whereas the electric potential at contact 202c
is raised and therefore the signal 222a increases due to the action of a
positive Bx-field. Note that the output signal 222a is positive if the
input signal at the non-inverting input denoted with a "+" is larger than
the input signal at the inverting input denoted with a "-".

[0115] Suppose now that the magnetic field in the y-direction By>0 and
Bx=0: the Lorentz-Force on the electrons flowing through the tub portions
203ad and 203bc again pulls them to the surface of the tub, which
decreases the resistance of these tubs. The electrons flowing in the
other two branches of the tub, i.e., the tub portions 203ab and 203cd,
are not affected by the By-component because it is parallel to the drift
velocity. Consequently, the electric potential at the contact 202a is
raised and the electric potential at the contact 202c is lowered so that
the signal 222a decreases.

[0116] In summary, the output signal 222a is proportional to the
difference of the magnetic field components in the x- and y-directions Bx
and By: Sout(222a)=K*(Bx-By) with K>0. The factor of
proportionality K is equal for both components Bx and By as long as the
device has at least a 90° symmetry (in our case the tub portion
203ad is equally long as the tub portion 203ab). Changing the current
direction causes the output signal Sout(222a) to change its sign.

[0117] Exchanging or swapping the inputs and outputs of the ring-shaped
vertical Hall device results in the situation shown in FIG. 13B. If
Bx>0 and By=0, the resistances of the tub portions 203ab and 203cd
decrease and the output signal 222b is positive. If By>0 and Bx=0, the
resistances of the tub portions 203bc and 203ad increase and the output
signal 222b is positive. The output signal during the second operating
phase which is illustrated in FIG. 13B thus depends on the magnetic field
components in the x- and y-directions Bx and By, thus
Sout(222b)=K*(Bx+By).

[0118] The output signals of both operating phases can be subtracted:
Sout(222a)-Sout(222b)=K*(Bx-By)-K*(Bx+By)=(-2)*K*By.

[0119] At the same time, a zero-point error cancels or is significantly
reduced, as is shown next: suppose that the tub portion 203ab is slightly
longer than the other branches of the device. At vanishing magnetic
fields we get Sout(222a)=(-1)*Off and Sout(222b)=(-1)*Off with
Off>0. Therefore, the offset Off vanishes if the two signals for the
two operating phases are subtracted: Sout(222a)-Sout(222b)=0
(for Bx=By=0). Hence, the difference of the signal
Sout(222a)-Sout(222b) is proportional to the By field and it is
at the same time substantially free of the zero-point errors of the
device. This is the spinning current principle applied to ring-shaped
vertical Hal devices.

[0120] The current direction can be reversed in both FIGS. 13a and 13b in
order to have a total of four measuring points for all four current
directions. If all four values are subtracted an even better spinning
current method can be obtained with an output signal that is still
proportional to the magnetic field component in the y-direction By.

[0121] Generally, the connections can be changed in many permutations and
it is also possible to rotate the device on the wafer so that the
portions of the tub 103, 203 may be at an angle to the x-axis different
from 0° and 90°. The magnetic field components in the
x-direction Bx and the y-direction By can be measured separately and
simultaneously a very low offset error or zero-point error can be
achieved.

[0122] FIGS. 14a and 14b show another ring-shaped Hall device 300a, 300b
which is rotated by 45° compared to the ring-shaped Hall device
200a, 200b shown in FIGS. 13a and 13b. The abbreviations nx and ny are
used to designate the unit vectors in the x-direction and the
y-direction, respectively. If the magnetic field points into the
direction (nx+ny)/sqrt(2), the resistances of the tub portions 303ad and
303bc decrease and thus the output signal 322a is negative.

[0123] If the magnetic field points into the direction (nx-ny)/syrt(2) the
resistances of the tub portions 303ab and 303cd decrease and thus the
output signal 322a is positive.

[0124] From this it follows that
Sout(322a)=-K*(Bx+By)/sqrt(2)+K*(Bx-By)/sqrt(2)=-sqrt(2)*K*By with
K>0.

[0125] Exchanging or swapping the inputs and the outputs of the device
leads to the configuration which is shown in FIG. 14B that is used during
the second operating phase of the spinning current scheme, for example.

[0126] If the magnetic field points into the direction (nx+ny)/sqrt(2),
the resistances of the tub portions 303ad and 303bc increase and thus the
output signal 322b is positive.

[0127] If the magnetic field points into the direction (nx-ny)/sqrt(2),
the resistances of the tub portions 303ab and 303cd decrease and thus the
output signal 322b is positive.

[0128] It follows that
Sout(322b)=K*(Bx+By)/sqrt(2)+K*(Bx-By)/sqrt(2)=sqrt(2)*K*Bx with
K>0.

[0129] As with the ring-shaped vertical Hall device 200a, 200b shown in
FIGS. 13a, 13b, the zero-point error or offset can be significantly
reduced which can be demonstrated by similar calculations. Supposing
again that the tub portion 303ab is slightly longer than the other
branches, at zero magnetic field the two output signals for the two
operating phases are: Sout(322a)=(-1)*Off and
Sout(322b)=(-1)*Off with Off>0.

[0130] Therefore, this zero-point error can be cancelled by subtracting
the output signals of the two operating phases;
Sout(322a)-Sout(322b). This leads to the following equation:

[0131] The ring-shaped vertical Hall devices 200 and 300 shown in FIGS.
13a, 13b and 14a, 14b, respectively, may be combined to form a
measurement system. Such a measurement system including both devices 200
and 300 is capable of computing the magnetic field components Bx and By
separately. It is possible to arrange both devices side-by-side. Yet, one
may also place one device inside the inner perimeter of the other device
in order to have identical centers of symmetry 105.

[0132] The vertical Hall sensors or devices disclosed herein may be
modified or further specified by means of one or more of the following
configurations, structures, and/or measures. One or more p-isolation tubs
may be inserted between the n.sup.+ contacts, i.e., between any two or
more contacts that are formed in or on the surface of the Hall effect
region or tub. The p-isolation tubs may be used to achieve a certain
desired current density distribution within the Hall effect region or
tub, for example by preventing that a significant portion of the electric
current flows near the surface of the Hall effect region or tub.

[0133] Especially with respect to the ring-shaped vertical Hall devices
100, 200, 300 shown in FIGS. 12a to 14b, the tubs may be circular or
octagonal. As another option, a multitude of ring-shaped vertical Hall
devices may be used. The multitude of ring-shaped vertical Hall devices
may be arranged in an array, a grid, or a cross-shaped arrangement, for
example.

[0134] The vertical Hall sensors or devices may comprise an n.sup.+ buried
layer (nBL) or not. If an n.sup.+ buried layer is present, this n.sup.+
buried layer may be interrupted between the different sections of a Hall
effect region or portions of a tub, if this is technologically feasible
with the semiconductor manufacturing process used for manufacturing a
particular vertical Hall effect sensor or device.

[0135] With respect to the ring-shaped vertical Hall devices, the number
of contacts may be reduced to three contacts only. In this case, the
ring-shaped vertical Hall device would comprise two supply contacts and
only one sense contact. Instead of measuring a differential sense signal
between two sense contacts, a sense signal would be measured at the
single sense contacts referred to a reference potential, such as a ground
potential.

[0136]FIG. 15 shows a schematic flow diagram of a magnetic sensing method
according to an embodiment of the teachings disclosed herein. During a
first action 152 a power supply is connected between a spinning current
contact and a supply-only contact of a Hall effect region. The spinning
current contact is configured to function alternatingly as a supply
contact and as a sense contact according to the spinning current scheme.
The spinning current contact and the sense contact belong to a plurality
of contacts formed in or on the surface of the Hall effect region of a
vertical Hall sensor comprising at least four spinning current contacts
and at least two supply-only contacts. The contacts are arranged in a
sequence along a path extending between a first end and a second end of
the Hall effect region, wherein the at least four spinning current
contacts are arranged along a central portion of the path, and wherein
the at least two supply-only contacts are arranged on both sides of the
central portion in a distributed manner. The supply-only contacts are
configured to supply electrical energy to the Hall effect region
according to an extension of the spinning current scheme for supplying
electrical energy to the Hall effect region.

[0137] A sense signal is sensed during an action 154 between at least two
spinning current contacts currently functioning as sense contacts.

[0138] Then, at an action 156, the functions of the spinning current
contacts are swapped so that the electrical energy is now supplied to the
Hall effect region via one of the spinning current contacts that has
previously functioned as a sense contact and at least one other
supply-only contact different from the supply-only contact used
previously, i.e., during the actions 152 and 154.

[0139] During an action 158 another sense signal is sensed between two
spinning current contacts other than the ones used previously as sense
contacts.

[0140] At an action 159 an output signal is determined on the basis of the
sense signals obtained during the actions 154 and 158. The magnetic
sensing method may then be repeated for another cycle of the spinning
current scheme.

[0141] Although some aspects have been described in the context of an
apparatus, it is clear that these aspects also represent a description of
the corresponding method, where a block or device corresponds to a method
step or a feature of a method step. Analogously, aspects described in the
context of a method step also represent a description of a corresponding
block or item or feature of a corresponding apparatus. Some or all of the
method steps may be executed by (or using) a hardware apparatus, like for
example, a microprocessor, a programmable computer or an electronic
circuit. In some embodiments, some one or more of the most important
method steps may be executed by such an apparatus.

[0142] The above described embodiments are merely illustrative for the
principles of the present invention. It is understood that modifications
and variations of the arrangements and the details described herein will
be apparent to others skilled in the art. It is the intent, therefore, to
be limited only by the scope of the impending patent claims and not by
the specific details presented by way of description and explanation of
the embodiments herein.